1. Field of the Invention
The invention relates to a circuit arrangement for steepening signal slopes of a digital signal in the form of a sequence of amplitude-discrete sampling values of an analog signal.
2. Description of the Related Art
A circuit arrangement for enhancing the sharpness of colour edges in which the shape of the luminance signal is utilized to steepen signal slopes of the chrominance signal is known from DE-C 35 41 103. To this end the steepness of the luminance signal is determined and a counter is activated when a given steepness value is exceeded. During the period in which the counter continues to count, a prefixed value of the color difference signal is released, independently of the continuous variations of the chrominance signal. After counting a given number of clocks, the actual color difference signal value is released again. Thus, starting from the initial amplitude of the signal, there is a direct change-over to the final value. Such a circuit arrangement is particularly unable to adapt to varying signal characteristics. For example, the length of a signal slope, or its steepness, is not taken into account. Moreover, particularly in the case of signal slopes having a relatively low frequency, i.e. those having a relatively long rise time, a signal alienation is to be taken into account because these slopes are also subjected to the steepening operation. However, the fundamental problem of the known circuit arrangement is that it operates in conjunction with the luminance signal, so that color variations which are not caused by a variation of the luminance signal cannot be steepened.